<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <todo-item></todo-item>
    </div>
</body>
<script src="https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.js"></script>
<script>
    Vue.component('todo-item',{
        template: '<li>这是个待办项</li>'
    })
    var app = new Vue({
        el:"#app"
    })
</script>
</html>